Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.lucene.search.spans; import java.io.IOException; import java.util.Map; import java.util.Objects; import java.util.Set; import org.apache.lucene.index.IndexReader; import org.apache.lucene.index.LeafReaderContext; import org.apache.lucene.index.Term; import org.apache.lucene.index.TermStates; import org.apache.lucene.search.BooleanClause; import org.apache.lucene.search.DocIdSetIterator; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.Query; import org.apache.lucene.search.QueryVisitor; import org.apache.lucene.search.ScoreMode; import org.apache.lucene.search.TwoPhaseIterator; /** Removes matches which overlap with another SpanQuery or which are * within x tokens before or y tokens after another SpanQuery. */ public final class SpanNotQuery extends SpanQuery { private SpanQuery include; private SpanQuery exclude; private final int pre; private final int post; /** Construct a SpanNotQuery matching spans from <code>include</code> which * have no overlap with spans from <code>exclude</code>.*/ public SpanNotQuery(SpanQuery include, SpanQuery exclude) { this(include, exclude, 0, 0); } /** Construct a SpanNotQuery matching spans from <code>include</code> which * have no overlap with spans from <code>exclude</code> within * <code>dist</code> tokens of <code>include</code>. Inversely, a negative * <code>dist</code> value may be used to specify a certain amount of allowable * overlap. */ public SpanNotQuery(SpanQuery include, SpanQuery exclude, int dist) { this(include, exclude, dist, dist); } /** Construct a SpanNotQuery matching spans from <code>include</code> which * have no overlap with spans from <code>exclude</code> within * <code>pre</code> tokens before or <code>post</code> tokens of * <code>include</code>. Inversely, negative values for <code>pre</code> and/or * <code>post</code> allow a certain amount of overlap to occur. */ public SpanNotQuery(SpanQuery include, SpanQuery exclude, int pre, int post) { this.include = Objects.requireNonNull(include); this.exclude = Objects.requireNonNull(exclude); this.pre = pre; this.post = post; if (include.getField() != null && exclude.getField() != null && !include.getField().equals(exclude.getField())) throw new IllegalArgumentException("Clauses must have same field."); } /** Return the SpanQuery whose matches are filtered. */ public SpanQuery getInclude() { return include; } /** Return the SpanQuery whose matches must not overlap those returned. */ public SpanQuery getExclude() { return exclude; } @Override public String getField() { return include.getField(); } @Override public String toString(String field) { StringBuilder buffer = new StringBuilder(); buffer.append("spanNot("); buffer.append(include.toString(field)); buffer.append(", "); buffer.append(exclude.toString(field)); buffer.append(", "); buffer.append(Integer.toString(pre)); buffer.append(", "); buffer.append(Integer.toString(post)); buffer.append(")"); return buffer.toString(); } @Override public SpanWeight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException { SpanWeight includeWeight = include.createWeight(searcher, scoreMode, boost); SpanWeight excludeWeight = exclude.createWeight(searcher, ScoreMode.COMPLETE_NO_SCORES, boost); return new SpanNotWeight(searcher, scoreMode.needsScores() ? getTermStates(includeWeight) : null, includeWeight, excludeWeight, boost); } public class SpanNotWeight extends SpanWeight { final SpanWeight includeWeight; final SpanWeight excludeWeight; public SpanNotWeight(IndexSearcher searcher, Map<Term, TermStates> terms, SpanWeight includeWeight, SpanWeight excludeWeight, float boost) throws IOException { super(SpanNotQuery.this, searcher, terms, boost); this.includeWeight = includeWeight; this.excludeWeight = excludeWeight; } @Override public void extractTermStates(Map<Term, TermStates> contexts) { includeWeight.extractTermStates(contexts); } @Override public Spans getSpans(final LeafReaderContext context, Postings requiredPostings) throws IOException { Spans includeSpans = includeWeight.getSpans(context, requiredPostings); if (includeSpans == null) { return null; } Spans excludeSpans = excludeWeight.getSpans(context, requiredPostings); if (excludeSpans == null) { return includeSpans; } TwoPhaseIterator excludeTwoPhase = excludeSpans.asTwoPhaseIterator(); DocIdSetIterator excludeApproximation = excludeTwoPhase == null ? null : excludeTwoPhase.approximation(); return new FilterSpans(includeSpans) { // last document we have checked matches() against for the exclusion, and failed // when using approximations, so we don't call it again, and pass thru all inclusions. int lastApproxDoc = -1; boolean lastApproxResult = false; @Override protected AcceptStatus accept(Spans candidate) throws IOException { // TODO: this logic is ugly and sneaky, can we clean it up? int doc = candidate.docID(); if (doc > excludeSpans.docID()) { // catch up 'exclude' to the current doc if (excludeTwoPhase != null) { if (excludeApproximation.advance(doc) == doc) { lastApproxDoc = doc; lastApproxResult = excludeTwoPhase.matches(); } } else { excludeSpans.advance(doc); } } else if (excludeTwoPhase != null && doc == excludeSpans.docID() && doc != lastApproxDoc) { // excludeSpans already sitting on our candidate doc, but matches not called yet. lastApproxDoc = doc; lastApproxResult = excludeTwoPhase.matches(); } if (doc != excludeSpans.docID() || (doc == lastApproxDoc && lastApproxResult == false)) { return AcceptStatus.YES; } if (excludeSpans.startPosition() == -1) { // init exclude start position if needed excludeSpans.nextStartPosition(); } while (excludeSpans.endPosition() <= candidate.startPosition() - pre) { // exclude end position is before a possible exclusion if (excludeSpans.nextStartPosition() == NO_MORE_POSITIONS) { return AcceptStatus.YES; // no more exclude at current doc. } } // exclude end position far enough in current doc, check start position: if (excludeSpans.startPosition() - post >= candidate.endPosition()) { return AcceptStatus.YES; } else { return AcceptStatus.NO; } } }; } @Override public void extractTerms(Set<Term> terms) { includeWeight.extractTerms(terms); } @Override public boolean isCacheable(LeafReaderContext ctx) { return includeWeight.isCacheable(ctx) && excludeWeight.isCacheable(ctx); } } @Override public Query rewrite(IndexReader reader) throws IOException { SpanQuery rewrittenInclude = (SpanQuery) include.rewrite(reader); SpanQuery rewrittenExclude = (SpanQuery) exclude.rewrite(reader); if (rewrittenInclude != include || rewrittenExclude != exclude) { return new SpanNotQuery(rewrittenInclude, rewrittenExclude, pre, post); } return super.rewrite(reader); } @Override public void visit(QueryVisitor visitor) { if (visitor.acceptField(getField())) { include.visit(visitor.getSubVisitor(BooleanClause.Occur.MUST, this)); exclude.visit(visitor.getSubVisitor(BooleanClause.Occur.MUST_NOT, this)); } } /** Returns true iff <code>o</code> is equal to this. */ @Override public boolean equals(Object other) { return sameClassAs(other) && equalsTo(getClass().cast(other)); } private boolean equalsTo(SpanNotQuery other) { return include.equals(other.include) && exclude.equals(other.exclude) && pre == other.pre && post == other.post; } @Override public int hashCode() { int h = classHash(); h = Integer.rotateLeft(h, 1); h ^= include.hashCode(); h = Integer.rotateLeft(h, 1); h ^= exclude.hashCode(); h = Integer.rotateLeft(h, 1); h ^= pre; h = Integer.rotateLeft(h, 1); h ^= post; return h; } }